Image forming material, method and device for removing images, and image forming process and apparatus

ABSTRACT

An image forming material for forming an image on an image recording material with an image binding force being established between the image and the image recording material, the image forming material containing an image forming substance, and a binding force reducing substance which reduces the image binding force when the image is heated. A method of removing an image formed on an image recording material with a binding force being established between the image and the recording material by contacting a stripping member with the image with heating under pressure. A binding force reducing substance may be contained in the surface of the stripping member or in the image recording material.

BACKGROUND OF THE INVENTION

This invention relates generally to an image forming material and, morespecifically, to an image forming material for forming a stable image onan image recording material by, for example, ordinary printing such asletterpress printing or lithographic printing, electrophotography, inkjet printing, thermal transfer recording or writing such as with crayonor pens, wherein the image is able to be removed from the imagerecording material. The present invention is also directed to a methodfor removing an image on an image recording material, to a device forcarrying out the method, to a process for forming an image and to anapparatus for carrying out the process.

With rapid progress of various information recording and transmittingmeans, the level of information output has very increased and paperconsumption has increased significantly. In an effort to reduce theconsumption of paper and to conserve forest resources, recycling ofwaste paper is now an important concern. Thus, many methods have beenhitherto proposed to recycle waste papers, especially tonerimage-bearing papers produced by electrophotography.

One known method is to treat a paper to improve erasability of the tonerimages. Such a method has a problem because the recyclable paper is notavailable at a low cost. Another method is to use an erasable tonerwhose color is erasable by irradiation thereof with a light (JapanesePatent No. 2,960,229). This method has a problem because the discoloredmaterial remaining on the paper adversely affect the surface smoothnessthereof so that it is difficult to reuse same for image formation.Japanese Laid-Open Patent Publication No. H08-146649 proposes a tonercontaining a surfactant to improve water absorbing efficiency. Thistoner, however, requires a wet treatment to remove the toner images fromthe image-bearing recording material and, therefore, has a problembecause the size of the paper increases due to swelling.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide an imageforming material which can form a stable and high grade image on anordinary image recording material such as plain paper and which permitsthe removal of the image from the recording material.

Another object of the present invention is to provide an image formingmaterial of the above-mentioned type which permits the removal of theimage from the recording material without using a wet treatment andwhich allows for the reuse of the recording material for imageformation.

It is a further object of the present invention to provide a simplemethod and a device for removing an image from an image-bearingrecording material.

It is yet a further object of the present invention to provide a processand a apparatus for forming an image on an image recording material.

In accomplishing the foregoing objects, there is provided in accordancewith one aspect of the present invention an image forming material forforming an image on an image recording material with an image bindingforce being established between said image and said image recordingmaterial, said image forming material comprising an image formingsubstance, and a binding force reducing substance which reduces saidimage binding force when said image is heated.

In another aspect, the present invention provides a method of removingan image of an image forming material according to claim 1 formed on animage recording material, said method comprising the steps of:

-   -   contacting a stripping member under pressure with said image on        said image recording material while heating said image to reduce        said image binding force; and    -   peeling said image recording material from said stripping member        to transfer said image from said image recording material to        said stripping member.

The present invention also provides a method of removing an image of animage forming material formed on an image recording material with animage binding force being established between said image and said imagerecording material, said method comprising the steps of:

-   -   providing a stripping member having a surface resin layer        comprising a binding force reducing substance, said binding        force reducing substance being adapted to reduce said image        binding force when said image is heated in the presence of said        binding force reducing substance;    -   contacting said surface of said stripping member under pressure        with said image on said image recording material while heating        said image to reduce said image binding force established        between said image and said image recording material; and    -   peeling said image recording material from said stripping member        to transfer said image from said image recording material to        said stripping member.

In a further aspect, the present invention provides a device forremoving an image of the above image forming material formed on an imagerecording material, said device comprising:

-   -   a stripping member providing an adhesion strength between said        stripping member and said image which is not smaller than said        image binding force;    -   means for contacting said stripping member with said image on        said image recording material under pressure;    -   a heater for heating said image during its contact with said        stripping member under pressure, thereby reducing said binding        force; and    -   drive means for separating said image recording material from        said stripping member so that said image is transferred from        said image recording material to said stripping member.

In a further aspect, the present invention provides a device forremoving an image of an image forming material formed on an imagerecording material with an image binding force being established betweensaid image and said image recording material, said device comprising:

-   -   a stripping member having a surface layer comprising a binding        force reducing substance adapted to reduce said image binding        force when said image is heated in the presence of said binding        force reducing substance, said surface layer is adapted to        release said binding force reducing substance when heated so        that an adhesion strength which is not smaller than said image        binding force is established between said stripping member and        said image after the release of said binding force reducing        substance;    -   means for contacting said stripping member with said image on        said image recording material under pressure;    -   a heater for heating said image during its contact with said        stripping member under pressure, thereby reducing said binding        force established between said image and said image recording        material; and    -   drive means for separating said image recording material from        said stripping member so that said image is transferred from        said image recording material to said stripping member.        In a further aspect, the present invention provides an image        forming process comprising depositing the above image forming        material on an image recording material. In a further aspect,        the present invention provides an image forming process        comprising depositing an image forming material on an image        recording material, and removing the image formed on said image        recording material in accordance with the above image removing        method to obtain a recycled recording material, and forming an        image on said recycled recording material.

In a further aspect, the present invention provides an image formingprocess comprising forming an image on an image recording material withan image binding force being established between said image and saidimage recording material, wherein before said image is formed, a bindingforce reducing substance is deposited on said image recording material,said binding force reducing substance reducing said image binding forcewhen said image is heated.

In a further aspect, the present invention provides an image formingapparatus comprising an image forming device for forming an image on animage recording material, and the above image removing device.

In a further aspect, the present invention provides an image formingprocess comprising forming an image on an image recording material withan image binding force being established between said image and saidimage recording material, wherein before said image is formed, a bindingforce reducing substance is deposited on said image recording material,said binding force reducing substance reducing said image binding forcewhen said image is heated.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome apparent from the detailed description of the preferredembodiments of the invention which follows, when considered in the lightof the accompanying drawing, in which:

FIG. 1 is a cross-sectional view diagrammatically illustrating anembodiment of an image removing device according to the presentinvention connected to an image forming apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

According to the present invention, an image formed on an imagerecording material with a binding force being established between theimage and the recording material is removed by contacting a strippingmember with the image with heating under pressure. As a consequence ofsuch a contact, the image is softened to reduce the binding force whileincreasing an adhesion strength between the image and the strippingmember.

In one preferred embodiment, the heating under pressure is carried outin the presence of a binding force reducing substance. The binding forcereducing substance which is present in an interface between the imageand the recording material reduces the binding force established betweenthe image and the recording material to permit the removal of the imagefrom the recording material. Thus, when the recording material is peeledfrom the stripping member, the image is transferred from the recordingmaterial to the stripping member. The resulting recording material maybe recycled.

It is desirable that the image binding force is reduced to 2.0 kg/cm² orless by the heating for reasons of completely removing the image fromthe image recording material. It is also desirable that the imagebinding force is 1 to 4.5 kg/cm² or less at room temperature.

As used herein the term “image binding force” is measured using a probetack tester (Model TAC-II manufactured by Reska Inc.). The image bindingforce at room temperature is measured as follows. A pressure sensitiveadhesive double coated tape is adhered to a tip (diameter: 5 mm) of aprobe of the tester. The probe is extended at a rate of 120 mm/min,pressed against the sample at a probe contact pressure of 500 gf perarea of the probe tip for a dwell time of 10 seconds and then retractedat a rate of 600 mm/min. The force required to free the probe from thesample (i.e. to remove the image from the recording material), measuredin grams/cm², is read from the indicator on the tester. These steps areperformed at room temperature. The image binding force at elevatedtemperature is measured in the same manner as above except that a 100 μmthick stripping film made of a polyether ether ketone (SUMILITE FS-1100Cmanufactured by Sumitomo Bakelite Inc.) is bonded on a tip of the probein place of the double coated tape and that the test is conducted at agiven elevated temperature.

In another preferred embodiment, the present invention provides an imageforming material for forming an image on an image recording materialwith an image binding force being established between the image and theimage recording material, wherein the image forming material comprisesan image forming substance, and a binding force reducing substance whichreduces the image binding force when the image is heated. With thisembodiment, the image recording material need not be specificallytreated. Further, mere heating under pressure is sufficient to removethe image. Such a removal treatment may be suitably carried out using atoner image fixing device.

It is preferred that the image forming substance further comprises abinder resin. The binder resin serves to provide sufficient cohesiveforce in the heated image layer so that the image is not destroyedduring peeling thereof from the image recording material. To maintain asuitable cohesive force, the binder resin is preferably such that theimage formed from the binder resin-containing image forming substancehas a viscoelasticity of 10⁴ Pa to 10⁶ Pa when heated for the removal ofthe image from the recording material. The binder resin is preferably athermally crosslinked resin to attain suitable viscoelasticity.

A toner for use in electrophotography generally contains a binder and acolorant and is suitably used as the image forming substance of theimage forming material of the present invention. When the image formingmaterial is a crayon as an writing instrument or a thermal transferribbon as a thermal transfer recording using a thermal head, the use ofa binder resin is preferred.

The binding force reducing substance is preferably a low melting pointsubstance. When the image is heated at a temperature higher than thesoftening point of the low melting point substance, the low meltingpoint substance is melted during heating and is easily located in aninterfase between the image and the recording material to preventbinding of the image to the recording material and to permit easyremoval of the image from the recording material. When the image hasbeen fixed to the recording material by heating under pressure, such asin the case of toner image fixation, the low melting point substanceserves to prevent establishment of an excessively high binding forcebetween the image and the recording material. It is preferred that thelow melting point substance, when melted, should not function as asolvent for components of the image forming substance, since otherwisethe binding force between the image and the recording material wouldundesirably excessively increase.

It is preferred that a low melting point substance have a hydrophilicgroup when the image forming substance is a hydrophobic in nature, suchas a toner, since the low melting point substance when melted isseparated from the image to accelerate the accumulation of the lowmelting point substance in the interface between the image and therecording material. In addition, when the recording material is made ofcellulose, the melted low melting point substance having hydrophilicgroups facilitate the removal of the image from the recording material.Although not wishing to be bound by the theory, the hydrophilic groupsof the low melting point substance are considered to interact with thehydroxyl groups of the cellulose through hydrogen bonding, therebypreventing the penetration of the low melting point substance deep intothe recording material.

It is also preferred that the low melting point substance have bothhydrophilic and hydrophobic (lipophilic) groups, especially when theimage forming substance and/or the stripping member have lipophilic(hydrophobic) groups, since the amount of the low melting pointsubstance remaining on the recording material after the transfer of theimage from the recording material to the stripping member is reduced andsince the recyclability of the recording material may be improved.

The low melting point substance is preferably a compound represented bythe following formula:(R)_(n).(Z)_(m)wherein R represents an organic group, Z is a hydrophilic group, n is aninteger of 1 to 3 determined according to the valency of Z, and m is aninteger of at least 1.

In the above formula, R is preferably selected from —PO₃H₂, ═POH, —OH,—O—, —COOH, —CH(OH)CH₂COOH, —OCOY (where Y is an alkyl group which mayhave one or more substitutents, an aryl group which may have one or moresubstitutents, or an aralkyl group which may have one or moresubstitutents), —SO₃H, ═N⁺X⁻ (where X is a halogen atom), —CONH₂ and—NH₂, n is an integer of 1 to 3 determined according to the valency ofZ, and m is at least 1 but is 1 only when Z is ═PO₂H or ═N⁺X⁻.

In the above formula, R is preferably an alkyl group having 1 to 40carbon atoms, more preferably 3 to 30 carbon atoms, most preferably 6 to22 carbon atoms, or an aralkyl group having 7 to 40 carbon atoms, morepreferably 7 to 30 carbon atoms. The alkyl and aralkyl groups maycontain one or more halogen atoms such as fluorine atoms.

The low melting point substance is preferably a dialkyl compound havinga hydrophilic group, such as (R)₂PO₂H, for reasons of prevention ofabsorption of moisture. The low melting point substance is alsopreferably an aromatic group-containing compound for reasons ofprevention of absorption of moisture. The hydrophobicity (lipophilicity)and steric hindrance of the dialkyl groups and the aromatic group areconsidered to prevent water molecules from entering in the image formingmaterial so that the moisture absorbing property thereof is suppressed.When the image forming material for use in, for example, developingelectrostatic latent images has moisture absorbing properties and ishygroscopic in nature, a problem such as agglomeration thereof is apt tobe caused during storage. Thus, it is desirable that the image formingmaterial hardly absorbs water.

In a preferred embodiment, the image forming substance is in the form ofsolid particles, such as toner, while the low melting point substance isbound to outer surfaces of the solid particles. In this case, the lowmelting point substance is preferably present in an amount of 1 to 50%by weight, more preferably 5 to 20% by weight, based on the a totalweight of the image forming substance and the low melting pointsubstance for reasons of suitable binding force reducing efficiencyduring heating stage while maintaining suitable binding force duringnon-heating stage and, hence, suitable storage stability of theimage-bearing recording material.

In another embodiment, the image forming substance is in the form ofsolid particles, such as toner, while the low melting point substance iscontained in the solid particles. In this case, the low melting pointsubstance is preferably present in an amount of 5 to 75% by weight, morepreferably 10-30% by weight, based on the a total weight of the imageforming substance and the low melting point substance for reasons ofsuitable binding force reducing efficiency during heating whilemaintaining suitable binding force during non-heating.

The low melting point substance preferably has a melting point of 60 to150° C., more preferably 70 to 120° C. for reasons of suitable bindingforce reducing efficiency during heating while maintaining suitablebinding force during non-heating. The low melting point substance ispreferably in the form of powder having an average particle diameter of0.1 to 20 μm, more preferably 0.5-10 μm for reasons of ensuring suitableimage quality of the image forming substance and suitable binding forcereducing efficiency.

In another preferred embodiment, the image forming material comprises,in addition to the image forming substance and the binding forcereducing substance, fine support particles which are infusible or whichhave a melting point higher than that of the low melting pointsubstance. In this case, the low melting point substance is bound to thefine support particles to improve the binding force reducing efficiency.The fine support particles serve to reduce an adverse affect by the lowmelting point substance and to improve storage stability of theimage-bearing recording material. The binding of the low melting pointsubstance with the fine support particles may be, for example, ionicbonding or hydrogen bonding.

The fine support particles to which the low melting point substance isbound have preferably an average particle diameter of 0.1 to 20 μm, morepreferably 0.5-10 μm for reasons of ensuring suitable image quality ofthe image forming substance and suitable binding force reducingefficiency of the low melting point substance. The low melting pointsubstance is present in an amount of 10 to 90% by weight based on atotal weight of the low melting point substance and the fine supportparticles to ensure suitable binding force reducing effect duringheating.

The fine support particles to which the low melting point substance isbound may be bound to outer surfaces of the solid particles of the imageforming substance. In this case, the fine support particles to which thelow melting point substance is bound are present in an amount of 1 to50% by weight, preferably 5 to 30% by weight based on the a total weightof the image forming substance, the fine support particles and the lowmelting point substance for reasons of suitable binding force reducingeffect during heating while maintaining suitable binding force duringnon-heating.

Alternately, the fine support particles to which the low melting pointsubstance is bound may be contained in the solid particles of the imageforming substance. In this case, the fine support particles to which thelow melting point substance is bound are present in an amount of 5 to75% by weight, preferably 10 to 40% by weight, based on the a totalweight of the image forming substance, the fine support particles andthe low melting point substance for reasons of suitable binding forcereducing effect during heating while maintaining suitable binding forceduring non-heating.

As described previously, the low melting point substance preferably hashydrophilic groups and hydrophobic groups. In this case, it is alsopreferred that the fine support particles have hydrophilic groups forreasons of improved removal efficiency of the image from the recordingmaterial and improved moisture absorption-preventing effect. Althoughnot wishing to be bound by the theory, the hydrophilic groups of the lowmelting point substance are considered to interact with the hydrophilicgroups of the fine support particles through hydrogen bonding, so thatthe low melting point substance is bound by the fine support particlesduring heating, thereby preventing the penetration of the low meltingpoint substance into the recording material and reducing moistureabsorbing properties. In addition, the presence of the hydrophobicgroups in the low melting point substance can reduce the moistureabsorbing properties.

In another embodiment, the image forming material comprises, in additionto the image forming substance, the low melting point substance, finesupport particles which are infusible or which have a melting pointhigher than that of the low melting point substance, wherein the lowmelting point substance is held within the fine support particles.

In this case, too, the low melting point substance is preferably presentin an amount of 10 to 90% by weight based on a total weight of the lowmelting point substance and the fine support particles.

The fine support particles in which the low melting point substance isheld may be bound to outer surfaces of the solid particles of the imageforming substance. In this case, the fine support particles in which thelow melting point substance is held are preferably present in an amountof 1 to 50% by weight, more preferably 5 to 30% by weight, based on thea total weight of the image forming substance, the fine supportparticles and the low melting point substance.

Alternatively, the fine support particles in which the low melting pointsubstance is held may be contained in the solid particles of the imageforming substance. In this case, the fine support particles in which thelow melting point substance is held are preferably present in an amountof 5 to 75% by weight, more preferably 10 to 40% by weight, based on thea total weight of the image forming substance, the fine supportparticles and the low melting point substance. The fine supportparticles in which the low melting point substance is held preferablyhave an average particle diameter of 0.1 to 20 μm, more preferably0.5-10 μm.

In another embodiment, the fine support particles are porous particles.In this case, the low melting point substance is preferably incorporatedinto the pores of the fine support particles, since the amount of thelow melting point substance may be increased to facilitate the reductionof the image binding force between the image and the recording materialduring heating, while maintaining suitable image binding force duringnon-heating stage.

The fine support particles may be, for example, those of the followingmaterials various carbides, such as silicon carbide, boron carbide,titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide,tantalum carbide, niobium carbide, tungsten carbide, chromium carbide,molybdenum carbide, calcium carbide and diamond carbon random; variousnitrides such as boron nitride, titanium nitride and zirconium nitride;various bromides such as zirconium bromide; various oxides, such astitanium oxide, calcium oxide, magnesium oxide, zinc oxide, copperoxide, aluminum oxide, silica and colloidal silica; various sulfidessuch as molybdenum disulfide; various fluorides such as magnesiumfluoride and carbon fluoride; various metal soaps, such as aluminumstearate, calcium stearate, zinc stearate and magnesium stearate;various minerals such as talc and bentonite; various metals, such ascobalt, iron, nickel, aluminum, copper, lead, magnesium, tin, zinc,antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium,titan, tungsten and vanadium, and alloys thereof; various titanic acidcompounds, such as calcium titanate, magnesium titanate and strontiumtitanate; various polymer particles, which are formed into particles bya wet polymerization method such as an emulsion polymerization method, asoap-free emulsion polymerization method and a non-aqueous dispersionpolymerization method, and a vapor phase method, such as styrene,(metha)acrylic polymers, polyolefins, fluorine-containing (metha)acrylicpolymers, nitrogen-containing (metha)acrylic polymers, epoxy resins,silicone resins, benzoguanamine resins, melamine resin; various naturalpolymers, such as starch (sweet potato starch, potato starch, tapiocastarch, wheat starch, corn starch), mannan (devil's-tongue), seaweeds(funorin, agar, sodium alginate), plant mucilage (hibiscus, tragacanth,gum arabic), microbiological mucilage (dextran, levan), and protein(glue, gelatin, casein, collagen); various semi-synthetic polymers, suchas cellulose (viscose, methyl cellulose, ethyl cellulose, hydroxyethylcellulose, carboxy methyl cellulose), and starch (soluble starch,carboxy methyl starch, dialdehyde starch); and various syntheticpolymers such as polyvinyl alcohol, sodium polyacrylate, Polyethyleneoxide and isobutyrene-maleic anhydride copolymers. These fine supportparticles may be used alone or in combination. If desired, the aboveinorganic fine support particles may be treated by a known suitablemethod with a conventionally used hydrophobisizing agent, such as asilane coupling agent, a titanate coupling agent, silicone oil andsilicone vanish.

In another embodiment, the image forming substance is in the form ofsolid particles, wherein the low melting point substance is contained inouter peripheral regions of the solid particles, and wherein the lowmelting point substance is present in an amount of 5 to 75% by weightbased on the a total weight of the image forming substance and the lowmelting point substance. Since the low melting point substance ispresent predominantly in an outer region of each of the image formingsubstance particles, suitable binding force reducing effect isobtainable even when the amount of the low melting point substance issmall.

If desired, a charge controlling agent may be incorporated into the finesupport particles and/or low melting point substance to improvetransferability thereof to the image recording material. Any chargecontrolling agent customarily employed in the field ofelectrophotography may be used.

The image forming substance which includes a colorant and, optionally, abinder resin may be a toner for use in, for example, electrophotography,powder ink for solid ink jet recording, ink for thermal transferrecording, ink for ordinary printing such as letterpress printing orlithographic printing and other solid inks such as crayon. The imagerecording material on which images are formed with the above imageforming substance may be, for example, ordinary paper made of fibers andgenerally used with conventional copying machines and printers, or aplastic film for overhead projectors.

Description will be made of a toner which is a typical example of theimage forming substance.

The toner generally includes a colorant, a binder resin and optionalingredients such as a charge controlling agent, a release agent, amagnetic substance, a filler and a post treating agent.

The binder resin may be any thermoplastic resin used for conventionaltoners. Illustrative of suitable binder resins are a styrene-acryliccopolymer resin, a styrene resin, a (meth)acrylic resin, an olefinresin, a polyester resin, a polyamide resin, a polycarbonate resin, apolyether resin, a polysulfone resin, an epoxy resin, an urethane resin,a phenol resin, a urea resin, copolymers thereof and mixtures thereof.The binder resin generally has a number average molecular weight Mn ofabout 6,000 to 20,000 and a ratio Mw/Mn of the weight average molecularweight Mw to the number average molecular weight Mn of about 2 to 100.The above molecular weight and molecular weight distribution are,however, not restrictive and may be changed as long as toner havingdesired characteristics may be obtained.

A variety of types and colors of organic and inorganic pigments and dyesconventionally used in the art are usable as a colorant contained in thetoner of the invention.

Examples of usable black pigments include carbon black, cupric oxide,manganese dioxide, aniline black, activated carbon, non-magneticferrite, magnetic ferrite and magnetite.

Examples of usable yellow pigments include chrome yellow, zinc yellow,cadmium yellow, yellow oxide, mineral fast yellow, nickel titaniumyellow, NABLES YELLOW, NAPHTHOL YELLOW S, HANSA YELLOW G, HANSA YELLOW10G, benzidine yellow G, benzidine yellow GR, quinoline yellow lake,permanent yellow NCG and tartrazine lake.

Examples of usable orange pigments include chrome orange, molybdenumorange, permanent orange GTR, pyrazolone orange, VULCAN ORANGE,INDANTHRENE BRILLIANT ORANGE RK, benzidine orange G and INDANTHRENEBRILLIANT ORANGE GK.

Examples of usable red pigments include iron oxide red, cadmium red, redlead oxide, cadmium mercury sulfide, cadmium, permanent red 4R, LITHOLRED, pyrazolone red, WATCHING RED, calcium salt, lake red D, BRILLIANTCARMINE 6G, eosin lake, rhodamine lake B, alizarin lake and BRILLIANTCARMINE 3B.

Examples of usable violet pigments include manganese violet, fast violetR and methyl violet lake.

Examples of usable blue pigments include prussian blue, cobalt blue,alkali blue lake, victoria blue lake, phthalocyanine blue, metal-freephthalocyanine blue, phthalocyanine blue partial chlorine compound, FASTSKY BLUE and INDANTHRENE BLUE BC.

Examples of usable green pigments include chrome green, chrome oxide,pigment green B, malachite green lake and FANAL YELLOW GREEN G.

Examples of usable white pigments include zinc white, titanium oxide,antimony white and zinc sulfide.

Examples of usable extender pigments include powdery barytes, bariumcarbonate, clay, silica, white carbon, talc and alumina white.

As various types of dyes such as basic dyes, acid dyes, disperse dyesand direct dyes may be usable. Examples of such dyes include nigrosine,methylene blue, rose bengale, quinoline yellow and ultramarine blue.

These colorants may be used alone or in combination of plural types. Theamount of the colorant is generally 1 to 20 parts by weight, preferably,2 to 10 parts by weight, per 100 parts by weight of the binder resin ofthe toner for reasons of suitable image density and fixing properties.

Various types and colors of pigments and dyes, as listed below, areusable as the colorant of a transparent color toner.

Examples of usable yellow pigments include C.I.10316 (naphthol yellowS), C.I.11710 (HANSA YELLOW 10G), C.I.11660 (HANSA YELLOW 5G), C.I.11670(HANSA YELLOW 3G), C.I.11680 (HANSA YELLOW G), C.I.11730 (HANSA YELLOWGR), C.I.11735 (HANSA YELLOW A), C.I.11740 (HANSA YELLOW RN), C.I.12710(HANSA YELLOW R), C.I.12720 (PIGMENT YELLOW L), C.I.21090 (benzidineyellow), C.I.21095 (benzidine yellow G), C.I.21100 (benzidine yellowGR), C.I.20040 (permanent yellow NCG), C.I.21220 (VULCAN FAST YELLOW 5)and C.I.21135 (VULCAN FAST YELLOW R).

Examples of usable red pigments include C.I.12055 (STERLING I),C.I.12075 (permanent orange), C.I.12175 (LITHOL FAST ORANGE 3GL),C.I.12305 (permanent orange GTR), C.I.11725 (HANSA YELLOW 3R), C.I.21165(VULCAN FAST ORANGE GG), C.I.21110 (benzidine orange G), C.I.12120(permanent red 4R), C.I.1270 (PARA RED), C.I.12085 (FIRE RED), C.I.12315(BRILLIANT FAST SCARLET), C.I.12310 (permanent red FR2), C.I.12335(permanent red F4R), C.I.12440 (permanent red FRL), C.I.12460 (permanentred FRLL), C.I.12420 (permanent red F4RH), C.I.12450 (LIGHT FAST REDTONER B), C.I.12490 (permanent carmine FB) and C.I.15850 (BRILLIANTCARMINE 6B).

Examples of usable blue pigments include C.I.74100 (metal-freephthalocyanine blue), C1.74160 (phthalocyanine blue) and C.I.74180 (FASTSKY BLUE).

These colorants for the transparent color toner may be used alone or incombination of plural types. The amount of the colorant is generally inthe range of 1 to 10 parts by weight, preferably 2 to 5 parts by weight,per 100 parts by weight of the binder resin of the toner for reasons ofsuitable color density and suitable transparency.

As the release agent (anti-offset agent), there may be used any knownrelease agent used in the conventional toners. Examples of suitablerelease agents include low molecular weight polypropylene wax, lowmolecular weight polyethylene wax, low molecular weight oxidizedpolypropylene wax, low molecular weight oxidized polyethylene wax,candelilla wax, carnauba wax, rice wax, montan wax and derivativesthereof, paraffin wax and derivatives thereof, microcrystalline wax andderivatives thereof, sazol wax and oxidized derivatives thereof, curedcastor oil and derivatives thereof, 1,2-hydroxystearic acid, higherfatty acid wax and higher fatty acid ester wax.

These waxes may be used singly or in combination of two or more. Theamount of the release agent is generally in the range of 1 to 10 partsby weight, preferably 2 to 5 parts by weight, per 100 parts by weight ofthe binder resin contained in the toner, when the toner image is fixedusing an oil-less heat roll fixing device. The amount of the releaseagent is not specifically limited when fixation is carried out usingother types of fixing device.

The magnetic substance may be metals such as aluminum, cobalt, iron,lead, magnesium, zinc, nickel, antimony, beryllium, bismuth, cadmium,calcium, manganese, selenium, titanium, tungsten, vanadium, alloys,mixtures, oxides and calcined products (ferrite) of the above metals.The magnetic substance is generally used in an amount of 1 to 80 partsby weight, preferably of 5 to 60 parts by weight, per 100 parts byweight of the binder resin in the toner.

As the charge control agent, there may be used any charge control agentused in the conventional toners. Examples of charge-control agent for anegative charge-toner include chromium complex type azo dyes S-32, S-33,S-34, S-35, S-37, S-38, S-40 (Orient Kagaku Kogyo Co.); Aizen SpilonBlack TRH, Aizen Spilon Black BHH (Hodogaya Kagaku Co.); Kayaset BlackT-22, Kayaset Black 004 (Nihon Kagaku Co.); Copper phthalocyanine dyeS-39 (Orient Kagaku Kogyo Co.); chrome complexes of salicylic acid E-81,E-82 (Orient Kagaku Kogyo Co.); zinc complex E-84 (Orient Kagaku KogyoCo.); aluminum complex E-86 (Orient Kagaku Kogyo Co.); calix arenecompounds and the like. Examples of a charge-control agent for apositive charge-toner include Bontron N-01, Bontron P-51 (Orient KagakuKogyo Co.), and imidazole compounds.

The post treating agent is used as an external additive to be bound tosurfaces of toner particles. Examples of the post treating agent includecarbides such as silicon carbide, boron carbide, titanium carbide,zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide,niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide,calcium carbide and diamond carbon random; nitrides such as boronnitride, titanium nitride and zirconium nitride; bromides such aszirconium bromide; oxides such as titanium oxide, calcium oxide,magnesium oxide, zinc oxide, copper oxide, aluminum oxide, silica andcolloidal silica; sulfides such as molybdenum disulfide; fluorides suchas magnesium fluoride and carbon fluoride; metal soaps such as aluminumstearate, calcium stearate, zinc stearate and magnesium stearate;minerals such as talc and bentonite; metals such as cobalt, iron,nickel, aluminum, copper, lead, magnesium, tin, zinc, antimony,beryllium, bismuth, cadmium, calcium, manganese, selenium, titan,tungsten and vanadium; alloys of the above metals; polymer particles,which are formed into particles by a wet polymerization method such asan emulsion polymerization method, a soap-free emulsion polymerizationmethod and a non-aqueous dispersion polymerization method, and a vaporphase method, such as styrene, (metha)acrylic polymers, polyolefins,fluorine-containing (metha)acrylic polymers, nitrogen-containing(metha)acrylic polymers, epoxy resins, silicone resins, benzoguanamineresins, melamine resin and copolymers thereof. These post treatingagents may be used singly or in combination. The amount of the posttreating agent is generally 0.01-5 parts by weight, preferably 0.1-3parts by weight, per 100 parts by weight of the toner.

The toner may be prepared by any suitable known method such as agrinding method; a wet method such as a spray dry method, a granulationpolymerization method (emulsion polymerization or suspensionpolymerization) or an emulsion or dispersion granulation method; or amicrocapsule method. Specific examples of the method include amechanical method in which ingredients of the toner such as a binder anda colorant are melt-kneaded, solidified, ground and further processedwith a hybridizer or a mechanofusion; a spray dry method in whichingredients of the toner are dispersed in a solution of a toner binderdissolved in a solvent, the dispersion being subsequently spray dried;and a dispersion method in which an organic solvent solution, emulsionor dispersion containing ingredients of the toner such as a binder resinor a prepolymer thereof and wax is dispersed in an aqueous medium withstirring, preferably while applying shear forces to the wax, to formtoner particles which are subsequently separated and dried. The tonergenerally has a particle size of 3 to 20 μm, preferably 4 to 15 μm, morepreferably 6 to 12 μm.

For depositing or fixing the binding force reducing substance such as alow melting point substance to outer surfaces of particles of the imageforming substance such as a toner, the binding force reducing substance(which may be supported by fine support particles through binding toouter surfaces thereof or through incorporation therewithin) and theimage forming substance particles are separately prepared and then mixedwith each other using a surface modifying device such as a hybridizer oran Ang mill or a mixing device such as a Henschel mixer or a Hi-X mixer.For incorporation of the binding force reducing substance into particlesof the image forming substance, the binding force reducing substance ismixed with the ingredients of the image forming substance (such as acolorant and a binder in the case of a toner) and the mixture is thengranulated into a desired method such as a grinding method a wet methodsuch as a spray dry method, a granulation polymerization method(emulsion polymerization or suspension polymerization), or an emulsionor dispersion granulation method.

The binding force reducing substance may be supported to the finesupport particles by any method such as a surface modifying method. Onesuitable method is as follows. The fine support particles havinghydrophilic groups such as carboxylic acid groups are dispersed in aninsoluble solvent such as toluene. The binding force reducing substancehaving both hydrophilic groups and hydrophobic (lipophilic) groups isthen added to the dispersion and the mixture is heated at 90-95° C. withstirring so that the binding force reducing substance is bound to thefine support particles. The solvent is then removed from the mixture toleave solids which are subsequently ground, if necessary.

An image formed on an image recording material using the above-describedimage forming material may be removed by contacting a stripping memberunder pressure with the image on the image recording material whileheating the image to reduce the image binding force established betweenthe image and the image recording material. The image recording materialis then peeled from the stripping member so that the image istransferred from the image recording material to the stripping member.

When the image has been formed on the image recording material by fusingand fixing the image forming substance thereon likewise in the case of atoner image, the heating under pressure of the image is preferably at atemperature higher than the fixing temperature for reasons of improvedimage removing efficiency attributed to an increased possibility thatthe low melting point substance (binding force reducing substance) ispresent at the interface between the image and the recording material.

The stripping member may be in the form of a roller or a film. Thesurface of the roller or film to which the image is contacted may bemade of a resin similar to the binder resin contained in the image.Alternatively, an adhesive resin, a heat resisting resin or a metal suchas aluminum, copper, nickel, iron or an alloy may be used as the surfacematerial of the stripping member.

Examples of the adhesive resin include protein adhesives such as glue,gelatin, albumin and casein; carbohydrate adhesives such as starch,cellulose and complex polysaccharide (Arabian gum, tragacanth gum,etc.); thermoplastic adhesives such as vinyl acetate polymers andcopolymers, acrylic polymers and copolymers, ethylene copolymers,polyamides, polyesters and polyurethanes; rubber adhesives such aspolychloroprene, nitrile rubber, regenerated rubber, SBR and naturalrubber; pressure-sensitive adhesives such as rubber and acrylic polymersand copolymers; thermoplastic resins which are the same as or which havegood affinity with the resin contained in the image forming substance,such as vinyl acetate polymers and copolymers, (meth)acrylic polymersand copolymers, olefin polymers and copolymers, styrene polymers andcopolymers, styrene-acrylic copolymers, polyamides, polycarbonates,polysulfones, polyethers, epoxy resins, urea resins, polyesters andpolyurethanes; rubber adhesives such as polychloroprene, nitrile rubber,regenerated rubber, SBR and natural rubber; and titanium oxide-dispersedpoly(ethylene terephthalate). Films of polyether sulfone, polyetherimide, polysulfone, polyethylene terephthalate, aromatic polyamide orpolyether ether ketone may also be suitably used as the surface materialof the stripping member.

In a further embodiment, the material constituting the surface of thestripping member contains the above-described binding force reducingsubstance. In this case, an image formed on an image recording materialwith an image binding force being established between the image and theimage recording material is removed by contacting the surface of thestripping member under pressure with the image on the image recordingmaterial while heating the image to reduce the image binding force bythe action of the binding force reducing substance contained in thesurface of the stripping member, followed by peeling the image recordingmaterial from the stripping member to transfer the image from the imagerecording material to the stripping member. It is preferred that theimage formed on the image recording material be formed from an imageforming material of the type described in the foregoing which contains abinding force reducing substance. As described previously, the imagepreferably has a viscoelasticity of 10⁴ Pa to 10⁶ Pa at the time of theheating. Also, the image binding force is desirably reduced to 2.0kg/cm² or less by the heating. Further, the image preferably has beenformed on the image recording material by fusing and fixing the imageforming material thereon. The heating is preferably at a temperaturehigher than the fixing temperature at which the image has been formed onthe image recording material.

It is further preferred that the surface of the stripping membercomprise the binding force reducing substance and a thermoplastic resinwhich is preferably the same as or which has good affinity with theresin contained in the image forming substance, such as vinyl acetatepolymers and copolymers, (meth)acrylic polymers and copolymers, olefinpolymers and copolymers, styrene polymers and copolymers,styrene-acrylic copolymers, polyamides, polycarbonates, polysulfones,polyethers, epoxy resins, urea resins, polyesters and polyurethanes,since the image on the image recording material shows good adhesion tothe stripping member because of the similarity of the resins and sinceresin of the surface of the stripping member is prevented fromtransferring to the non-image portion (background portion) of the imagerecording material because of the presence of the binding force reducingsubstance in the stripping surface. The amount of the binding forcereducing substance is generally 1-75% by weight, preferably 5-20% byweight, based on a total weight of the binding force reducing substanceand the thermoplastic resin. It is preferred that the stripping memberhave a surface layer which contains the above binding force reducingsubstance and the thermoplastic resin and which is provided on a supportwhich is resistant to heat and tension and has dimensional stability.

FIG. 1 depicts a device for removing an image of an image formingmaterial formed on an image recording material 1. The device has astripping member 10 which, in the illustrated case, is an endless filmsupported by a drive roller 8, support rollers 9 and tension rollers 12and 14. Disposed in parallel with the drive roller 8 is a roller 11defining therebetween a nip through which the film (stripping member) 11passes and runs upon driving of the roller 8. The image recordingmaterial 1 bearing an image thereon is fed to the nip from a feed tray 2though feed rollers 3 and a guide plate 4, so that the image on theimage recording material 1 is contacted with the stripping member 10under pressure. A heater 7 is disposed in the drive roller 8 for heatingthe image on the recording material 1 during its contact with thestripping member 10 under pressure, thereby reducing the binding forceestablished between the image and the recording material 1 whileproviding an adhesion strength between the stripping member 10 and theimage which adhesion strength is not smaller than the image bindingforce. The recording material 1 is further driven by the roller 8 to bedischarged from the nip and separated from the stripping member LO sothat the image is transferred from the image recording material 1 to thestripping member 10. The image transferred to the stripping member 10 isremoved therefrom by a cleaning member such as a roller, blade or brush.Designated as 13 is a temperatures sensor electrically coupled to theheater 7 through a suitable control device, so that the nip may bemaintained at a desired temperature. The recording material 1 from whichthe image has been removed is collected and recycled to an image formingdevice 20 for forming an image thereon.

In another preferred embodiment, there is provided an image formingprocess which comprises forming an image on an image recording materialwith an image binding force being established between the image and theimage recording material, wherein before the image is formed, theabove-described binding force reducing substance is deposited on theinage recording material. The binding force reducing substance reducesthe image binding force when the image is heated so that the image canbe removed. Since the binding force reducing substance and an imageforming substance from which the image is formed are stored separatelyfrom each other, storage stability of the image forming substance is notadversely affected by the binding force reducing substance. In addition,it is possible to form images without using binding force reducingsubstance if image removal is not intended.

The following examples will further illustrate the present invention.

EXAMPLE 1

Toner (Imagio Toner Type 18 manufactured by Ricoh Company, Ltd.) as animage forming substance and C₁₇H₃₅PO₃H₂ powder having an averageparticle diameter of 3 μm as a binding force reducing substance weremixed using a mill to obtain a developer (an image forming material)containing 20% by weight of the binding force reducing substance basedon a total weight of the image forming substance and the low meltingpoint substance. Using the thus obtained developer, a toner image havingan image density of 1.2 was formed on plain paper (PPC paper Type 6200manufactured by Ricoh Company, Ltd.) at a paper feed rate of about 30mm/second. The temperature of the toner image fixing roll was about 100°C. The toner image was evaluated for fixation by scratching the imagebearing paper with a nail. The fixation was rated as follows:

-   -   A: the image is not removed at all    -   B: part of the image remains unremoved    -   C: the image is completely removed        The results are shown in Table 1.

The image bearing paper was then charged on an image removing deviceconstructed as shown in FIG. 1. The image removing device had astripping member 10 which was an endless film having a thickness of 100μm and made of a polyether ether ketone (SUMILITE FS-1100C manufaturedby Sumitomo Bakelite Inc.). The image bearing paper was passed throughthe nip between the rolls 8 and 11 at a feed rate of about 30 mm/secondto contact the image with the stripping member 10 while maintaining thedriving roll 8 at a temperature of about 110° C. and to remove the imagefrom the paper. The resulting paper was evaluated for removability ofthe image with naked eyes. The removability was rated as follows:

-   -   5: the image is entirely removed    -   4: the image is almost entirely removed with only a slight        portion thereof remaining unremoved    -   3: a part of the image remains unremoved    -   2: a significant portion of the image remains unremoved    -   1: the image almost entirely remains unremoved The results are        shown in Table 1.

EXAMPLE 2

Polyacrylic acid particles (as fine support particles) were dispersed intoluene. A binding force reducing substance (C₁₇H₃₅PO₃H₂ powder) wasthen added to the dispersion and the mixture was heated at 90-95° C.with stirring so that the C₁₇H₃₅PO₃H₂ was bound to the polyacrylic acidparticles. The toluene was then removed from the mixture to leave solidswhich were subsequently milled to obtain an external additive powderhaving an average particle size of 3 μm. The thus obtained externaladditive was mixed with toner (Imagio Toner Type 18 manufactured byRicoh Company, Ltd.) using a mill to obtain a developer having aC₁₇H₃₅PO₃H₂ content of 4% by weight and a polyacrylic acid content of 1%by weight based on a total weight of the toner and the externaladditive. Using the thus obtained developer, an image was formed on apaper and the image was removed from the paper in the same manner asdescribed in Example 1. The fixation and removability are shown in Table1.

EXAMPLE 3

Example 2 was repeated in the same manner as described except that theamount of the external additive was increased so that the developer hada C₁₇H₃₅PO₃H₂ content of 8% by weight and a polyacrylic acid content of2% by weight based on a total weight of the toner and the externaladditive. The results are shown in Table 1.

EXAMPLE 4

Example 2 was repeated in the same manner as described except that theamount of the external additive was increased so that the developer hada C₁₇H₃₅PO₃H₂ content of 16% by weight and a polyacrylic acid content of4% by weight based on a total weight of the toner and the externaladditive. The results are shown in Table 1. Further, the image was foundto have a binding force at room temperature of 1.0 kg/cm², a bindingforce at 110° C. of 0.7 kg/cm² and a viscoelasticity at 110° C. of 10⁴Pa to 10⁵ Pa.

EXAMPLES 5

Example 2 was repeated in the same manner as described except that theamount of the external additive was increased so that the developer hada C₁₇H₃₅PO₃H₂ content of 32% by weight and a polyacrylic acid content of8% by weight based on a total weight of the toner and the externaladditive. The results are shown in Table 1.

EXAMPLES 6 TO 9

Examples 2 to 5 were repeated in the same manner as described exceptthat polyacrylic acid particles were replaced by ethylene-methylmethacrylic acid (MMA) copolymer having an MMA content of 15 wt %. Theresults are summarized in Table 1.

EXAMPLE 10

Porous silica particles (as fine support particles) were dispersed intoluene. A binding force reducing substance (C₁₇H₃₅PO₃H₂ powder) wasthen added to the dispersion and the mixture was heated at 90-95° C.with stirring so that the C₁₇H₃₅PO₃H₂ was included in the silicaparticles. The toluene was then removed from the mixture to obtain anexternal additive powder having an average particle size of 3 μm. Thethus obtained external additive was mixed with toner (Imagio Toner Type18 manufactured by Ricoh Company, Ltd.) using a mill to obtain adeveloper having a C₁₇H₃₅PO₃H₂ content of 2.5% by weight and a silicacontent of 2.5% by weight based on a total weight of the toner and theexternal additive. Using the thus obtained developer, an image wasformed on a paper and the image was removed from the paper in the samemanner as described in Example 1. The fixation and removability areshown in Table 1.

EXAMPLES 11 TO 13

Example 10 repeated in the same manner as described except that theamounts of C₁₇H₃₅PO₃H₂ and silica were changed to obtain developershaving C₁₇H₃₅PO₃H₂ and silica contents of each 5% by weight (Example11), 10% by weight (Example 12) and 20% by weight (Example 13), based ona total weight of the toner and the external additive. The fixation andremovability are shown in Table 1.

The softening points of the binding force reducing substances used inExamples are as follows:

-   C₁₇H₃₅PO₃H₂: 96° C.-   C₁₆H₃₂(OH)₂: 72-74° C.-   C₂₁H₄₃COOH: 81° C.-   C₁₈H₃₇NH₂: 50-52-   (C₁₈H₃₇O)₂PO₂H: 79-81° C.-   (OH)₃BzCO₂C₁₈H₃₇: 103-104° C.

carnauba wax: 80-90° C. TABLE 1 Binding force reducing Fine supportingsubstance particles Amount Amount Example Compound (wt %) Compound (wt%) Fixation Removability 1 C₁₇H₃₅—PO₃H₂ 20 — — A 4 2 C₁₇H₃₅—PO₃H₂ 4Polyacrylic 1 A 3 acid 3 C₁₇H₃₅—PO₃H₂ 8 Polyacrylic 2 A 4 acid 4C₁₇H₃₅—PO₃H₂ 16 Polyacrylic 4 A 5 acid 5 C₁₇H₃₅—PO₃H₂ 32 Polyacrylic 8 B5 acid 6 C₁₇H₃₅—PO₃H₂ 4 Ethylene- 1 A 3 MMA copolymer 7 C₁₇H₃₅—PO₃H₂ 8Ethylene- 2 A 4 MMA copolymer 8 C₁₇H₃₅—PO₃H₂ 16 Ethylene- 4 A 5 MMAcopolymer 9 C₁₇H₃₅—PO₃H₂ 32 Ethylene- 8 B 5 MMA copolymer 10C₁₇H₃₅—PO₃H₂ 2.5 Porous 2.5 A 4 silica 11 C₁₇H₃₅—PO₃H₂ 5 Porous 5 A 5silica 12 C₁₇H₃₅—PO₃H₂ 10 Porous 10 A 5 silica 13 C₁₇H₃₅—PO₃H₂ 20 Porous20 B 5 silica

EXAMPLE 14

Example 4 was repeated in the same manner as described except that adiol (C₁₆C₃₂(OH)₂) was substituted for C₁₇H₃₅PO₃H₂. The results areshown in Table 2. The image was found to have a binding force at roomtemperature of 2.0 kg/cm² and a binding force at 110° C. of 1.4 kg/cm².

EXAMPLE 15

Example 4 was repeated in the same manner as described except that acarboxylic acid (C₂₁H₄₃—COOH) was substituted for C₁₇H₃₅PO₃H₂. Theresults are shown in Table 2. The image was found to have a bindingforce at room temperature of 5 kg/cm² or more and a binding force at110° C. of 2 kg/cm² or more, A significant portion of the image remainedunremoved after the image removing treatment.

EXAMPLE 16

Example 4 was repeated in the same manner as described except that anamine (C₁₈H₃₇NH₂) was substituted for C₁₇H₃₅PO₃H₂. The results are shownin Table 2. The image was found to have a binding force at roomtemperature of 5 kg/cm² or more and a binding force at 110° C. of 2kg/cm² or more. A significant portion of the image remained unremovedafter the image removing treatment.

EXAMPLE 17

Example 3 was repeated in the same manner as described except that thestripping member 10 had a surface layer (thickness: about 3 μm) formedof the developer of Example 3. Namely, the surface layer of thestripping member contained the binder of the toner and the C₁₇H₃₅PO₃H₂.The results are shown in Table 2.

EXAMPLE 18

Example 4 repeated in the same manner as described except that theremoval of the image was performed at a roll temperature of 120° C. Theresults are shown in Table 2. The image was found to have aviscoelasticity at 120° C. of less than 10⁴ Pa. A part of the imageremained unremoved after the image removing treatment.

EXAMPLE 19

Example 4 was repeated in the same manner as described except that aphosphinic acid ((C₁₇H₃₇O)₂PO₂H) was substituted for C₁₇H₃₅PO₃H₂. Theresults are shown in Table 2. It was confirmed that the externaladditive (particles of polyacrylic acid to which the phosphinic acid wasbound) did not aggregate when allowed to stand for 100 hours in achamber at 30° C. and a relative humidity of 90%. On the other hand,polyacrylic acid particles without the phosphinic acid formed aggregateswhen tested in the same manner as above.

EXAMPLE 20

Example 4 was repeated in the same manner as described except that anaromatic ester ((OH)₃BzCO₂C₁₈H₃₇; Bz designates a benzene nucleus) wassubstituted for C₁₇H₃₅PO₃H₂. The results are shown in Table 2. It wasconfirmed that the external additive (particles of polyacrylic acid towhich the aromatic ester was bound) did not aggregate when allowed tostand for 100 hours in a chamber at 30° C. and a relative humidity of90%.

EXAMPLE 21

Example 4 was repeated in the same manner as described except that theexternal additive had an average particle diameter of 10 μm. The resultsare shown in Table 2.

EXAMPLE 22

Example 4 was repeated in the same manner as described except that theexternal additive had an average particle diameter of 20 μm. The fixedimage was partly removed by scratching with a nail.

EXAMPLE 23

Example 1 was repeated in the same manner as described except that theamount of the C₁₇H₃₅PO₃H₂ was increased so that the developer had aC₁₇H₃₅PO₃H₁₂ content of 40% by weigh based on a total weight of thetoner and the C₁₇H₃₅PO₃H₂. The results are shown in Table 2.

COMPARATIVE EXAMPLE 1

Example 1 was repeated in the same manner as described except that thetoner was used by itself for the formation of image. Namely, C₁₇H₃₅PO₃H₂was not used at all. The results are shown in Table 2.

COMPARATIVE EXAMPLE 2

A toner having the same composition as that used in Example 1 exceptthat carnauba wax was additionally contained in an amount of 80% byweight was prepared. Using the wax-containing toner, image formation andremoval were carried out in the same manner as described in Example 1.The results are shown in Table 2.

COMPARATIVE EXAMPLE 3

Comparative Example 2 was repeated in the same manner as describedexcept that the amount of the carnauba wax was reduced to 60% by weight.The results are shown in Table 2.

COMPARATIVE EXAMPLE 4

A toner having the same composition as that used in Example 5 exceptthat the binding force reducing substance was not used at all wasprepared. Using the resulting toner, image formation and removal werecarried out in the same manner as described in Example 1. The resultsare shown in Table 2.

COMPARATIVE EXAMPLE 5

A toner having the same composition as that used in Example 9 exceptthat the binding force reducing substance was not used at all wasprepared. Using the resulting toner, image formation and removal werecarried out in the same manner as described in Example 1. The resultsare shown in Table 2.

COMPARATIVE EXAMPLE 6

A toner having the same composition as that used in Example 12 exceptthat the binding force reducing substance was not used at all wasprepared. Using the resulting toner, image formation and removal werecarried out in the same manner as described in Example 1. The resultsare shown in Table 2.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all the changes which come within the meaning and rangeof equivalency of the claims are therefore intended to be embracedtherein.

The teachings of Japanese Patent Application No. 2001-232576, filed Jul.31, 2001, inclusive of the specification, claims and drawing, are herebyincorporated by reference herein. TABLE 2 Binding force reducing Finesupporting substance particles Amount Amount Example Compound (wt %)Compound (wt %) Fixation Removability 14 C₁₆H₃₂—(OH)₂ 16 Polyacrylic 4 A4 acid 15 C₂₁H₄₃—COOH 16 Polyacrylic 4 A 2 acid 16 C₁₈H₃₇—NH₂ 16Polyacrylic 4 A 2 acid 17 C₁₇H₃₅—PO₃H₂  8 Polyacrylic 2 A 5 acid 18C₁₇H₃₅—PO₃H₂ 16 Polyacrylic 4 A 3 acid 19 (C₁₈H₃₇O)₂—PO₂H 16 Polyacrylic4 A 4 acid 20 (OH)₃BZ—CO₂C₁₈H₃₇ 16 Polyacrylic 4 A 3 acid 21C₁₇H₃₅—PO₃H₂ 16 Polyacrylic 4 A 5 acid 22 C₁₇H₃₅—PO₃H₂ 16 Polyacrylic 4B 5 acid 23 C₁₇H₃₅—PO₃H₂ 40 — — B 5 Comp. 1 — — — — A 1 Comp. 2 carnauba80 — — A 1 wax Comp. 3 carnauba 60 — — A 1 wax Comp. 4 — — Polyacrylic 8A 1 acid Comp. 5 — — Ethylene- 8 A 1 MMA copolymer Comp. 6 — — Porus 10A 1 silica

1-53. (canceled)
 54. An image forming material suitably applicable for amethod of removing an image which comprises contacting a strippingmember under pressure with an image recording material while heating theimage to reduce an image binding force established between the image andimage recording material; and peeling the image recording material fromthe stripping member to transfer the image from the image recordingmaterial to the stripping member, the image forming material comprising:an image forming substance; and a binding force reducing substance whichreduces the image binding force when the image is heated.
 55. An imageforming material as claimed in claim 54, wherein the image formingsubstance comprises a binder resin.
 56. An image forming material asclaimed in claim 54, wherein the binding force reducing substance is alow melting point substance which reduces the image binding force whenthe image is heated at a temperature higher than the softening point ofthe low melting point substance.
 57. An image forming material asclaimed in claim 56, wherein the low melting point substance has ahydrophilic group.
 58. An image forming material as claimed in claim 56,wherein the low melting point substance has a hydrophilic group and ahydrophobic group.
 59. An image forming material as claimed in claim 56,wherein the image forming substance is in the form of solid particles,wherein the low melting point substance is comprised in the solidparticles, and wherein the low melting point substance is present in anamount of 5 to 75% by weight based on a total weight of the imageforming substance and the low melting point substance.
 60. An imageforming material as claimed in claim 55, wherein the binder resin is athermally crosslinked resin.
 61. A method of removing an image of animage forming material formed on an image recording material with animage binding force being established between said image and said imagerecording material, the method comprising: providing a stripping memberhaving a surface resin layer comprising a binding force reducingsubstance, the binding force reducing substance being adapted to reducethe image binding force when the image is heated in the presence of thebinding force reducing substance; contacting the surface of thestripping member under pressure with the image on the image recordingmaterial while heating the image to reduce the image binding forceestablished between the image and the image recording material; andpeeling the image recording material from the stripping member totransfer the image from the image recording material to the strippingmember, wherein the image forming material comprises: an image formingsubstance; and a binding force reducing substance which reduces theimage binding force when the image is heated.
 62. A method as claimed inclaim 61, wherein the image has a viscoelasticity of 10⁴ Pa to 10⁶ Pa bysaid heating.
 63. A method as claimed in claim 61, wherein the imagebinding force is reduced to 2.0 kg/cm² or less by said heating.
 64. Amethod as claimed in claim 61, wherein the image has been formed on theimage recording material by fusing and fixing the image forming materialthereon.
 65. A method as claimed in claim 64, wherein the heating is ata temperature higher than the fixing temperature at which said image hasbeen formed on the image recording material.
 66. A device for removingan image of an image forming material formed on an image recordingmaterial, the device comprising. a stripping member providing anadhesion strength between the stripping member and the image which isnot smaller than the image binding force; means for contacting thestripping member with the image on the image recording material underpressure; a heater for heating the image during its contact with thestripping member under pressure, thereby reducing the binding force; anddrive means for separating the image recording material from thestripping member so that the image is transferred from the imagerecording material to the stripping member, wherein the image formingmaterial comprises: an image forming substance; and a binding forcereducing substance which reduces the image binding force when the imageis heated.
 67. A device for removing an image as claimed in claim 66,wherein the stripping member has a surface layer which comprises abinding force reducing substance adapted to reduce the image bindingforce when the image is heated in the presence of the binding forcereducing substance, the surface layer is adapted to release the bindingforce reducing substance when heated so that an adhesion strength whichis not smaller than the image binding force is established between thestripping member and the image after the release of the binding forcereducing substance.